Bidirectional high frequency variable speed drive for CHP (combined heating and power) and flywheel applications

Abstract

The present invention provides a bidirectional high frequency speed drive configured to connect to a utility grid and an electrical machine. The bidirectional high frequency variable speed drive comprises a plurality of inductors each configured to connect to respective phase outputs of the electrical machine, a first plurality of power switches connected to the plurality of inductors, a second plurality of power switches connected to the plurality of inductors, and a controller connected to the first and second plurality of power switches. The controller can generate control signals based on an operating status and a predetermined operating status of the electrical machine. The first output of the first plurality of power switches can be interleaved to a second output of the second plurality of power switches. The present invention also provides methods for the bidirectional high frequency speed drive and apparatuses used to perform the methods of the present invention.

What is claimed: 
     
       1. A bidirectional high frequency variable speed drive configured to connect to a utility grid and an electrical machine, comprising:
 a plurality of inductors each configured to connect to respective phase outputs of the electrical machine, the electrical machine driven by at least one phase; 
 a first plurality of power switches connected to the plurality of inductors; 
 a second plurality of power switches connected to the plurality of inductors; and 
 an electrical machine interfacing controller connected to the first and second plurality of power switches, the electrical machine interfacing controller controlling an operating speed of the electrical machine, and comprising a positive and a zero sequence controller, 
 wherein a first output of the first plurality of power switches are interleaved to a second output of the second plurality of power switches, and the controller generates control signals based on an operating status and a predetermined operating status of the electrical machine. 
 
     
     
       2. The bidirectional high frequency variable speed drive of  claim 1 , wherein the electrical machine comprises at least one of a single-phase generator, a split-phase generator, a three-phase generator, a single-phase motor, a split-phase motor or a three-phase motor. 
     
     
       3. The bidirectional high frequency variable speed drive of  claim 1 , wherein the operating status of the electrical machine is indicative of the operating speed of the electrical machine. 
     
     
       4. The bidirectional high frequency variable speed drive of  claim 1 , wherein the utility grid is configured to be operable at a first frequency and the electrical machine is configured to be operable at a second frequency that is higher than the first frequency. 
     
     
       5. The bidirectional high frequency variable speed drive of  claim 4 , wherein each of the first and second plurality of power switches is configured to operate at a switching frequency to increase the first frequency to the second frequency that is compatible with the electrical machine. 
     
     
       6. The bidirectional high frequency variable speed drive of  claim 5 , wherein the switching frequency is less than approximately 9 kilohertz (kHz). 
     
     
       7. The bidirectional high frequency variable speed drive of  claim 5 , wherein each of the first and second plurality of power switches is controlled by each of the control signals. 
     
     
       8. The bidirectional high frequency variable speed drive of  claim 7 , wherein the each of the control signals is generated by pulse width modulation. 
     
     
       9. The bidirectional high frequency variable speed drive of  claim 4 , wherein each of the first and second plurality of power switches is configured to operate at a switching frequency to reduce the second frequency to the first frequency that is compatible with the utility grid. 
     
     
       10. The bidirectional high frequency variable speed drive of  claim 1 , wherein the electrical machine interfacing controller comprises a predictive current controller to avoid controller latencies. 
     
     
       11. The bidirectional high frequency variable speed drive of  claim 10 , wherein the predictive current controller operates according to the operating speed of the electrical machine. 
     
     
       12. The bidirectional high frequency variable speed drive of  claim 1 , further comprising a utility grid interfacing controller configured to control a DC bus voltage supplied to a third plurality of power switches configured to connect to the utility grid. 
     
     
       13. The bidirectional high frequency variable speed drive of  claim 12 , wherein the utility grid interfacing controller controls the DC bus voltage supplied to the first and second plurality of power switches. 
     
     
       14. The bidirectional high frequency variable speed drive of  claim 13 , wherein the utility grid interfacing controller comprises a negative sequence controller. 
     
     
       15. A bidirectional high frequency variable speed drive configured to connect to a utility grid and an electrical machine, comprising:
 a plurality of inductors each configured to connect to respective phase outputs of the electrical machine, the electrical machine driven by at least one phase; 
 a first plurality of power switches connected to the plurality of inductors; 
 a second plurality of power switches connected to the plurality of inductors; 
 an electrical machine interfacing controller connected to the first and second plurality of power switches, wherein a first output of the first plurality of power switches are interleaved to a second output of the second plurality of power switches, and the electrical machine interfacing controller generates control signals based on an operating status and a predetermined operating status of the electrical machine; and 
 a utility grid interfacing controller configured to control a DC bus voltage supplied to a third plurality of power switches configured to connect to the utility grid, 
 wherein the utility grid interfacing controller controls a DC bus voltage supplied to the first and second plurality of power switches, and the utility grid interfacing controller comprises a negative sequence controller. 
 
     
     
       16. The bidirectional high frequency variable speed drive of  claim 15 , wherein the electrical machine interfacing controller comprises a predictive current controller to avoid controller latencies. 
     
     
       17. The bidirectional high frequency variable speed drive of  claim 16 , wherein the predictive current controller operates according to a speed of the electrical machine. 
     
     
       18. The bidirectional high frequency variable speed drive of  claim 15 , wherein the electrical machine interfacing controller comprises positive and a zero sequence controller.